Method of uniting metallic bodies



April 9, 1929- c. F. sHERwooD 1,708,193

METHOD OF UNITING METALLIC BODIES Filed May V, 1927 www Mr@ Patented Apr. I9, 1929.

UNITED STATES CHARLES FREDERIC SHERWOOD, F DETROIT, MICHIGAN.

METHOD 0F UNITING METALLIC BODIES.

' Application led May 7, 1927. Serial No. 189,698.

This invention relates to the joining of metallic bodies and particularly electrically 'conducting bodies.

One of the objects of the present invention is to permanently join electrically conducting bodies in such a manner that the electrical conductivity of the integral structure will be substantially the same throughout and also so that the bond between the con-l ducting parts will be permanent and not subject to corrosion.

Further objects and advantages of the present invention will be apparent from thefollowing description, reference being V had to the accompanying drawings wherein a preferred embodiment of one form of the present invention is clearly shown.

The accompanying drawings which will be described show the application of the present invention tothe pigtails or flexible conductors of a brush for dynamo electric machines. However, it will be understood that the invention is not limitedto dynamo brushes but is susceptible of other applications.

In the drawings:

Fig. l'is a side view, partly in section, showing` apparatus for briquetting metal powders for making a dynamo brush.

Fig. 2 is a View similar to Fig. 1 showing the apparatus in the final stage of operation.

Fig. 3 is a perspective view showing the briquetted form having flexible conductors or pigtails extending therefrom and resting upon a metal clip which is .to be attached to the ends of the pigtails by the use of the present invention.

Fig. 4 is a sectional view taken in the,

plane of the lines A-B and C-D of Fig. 3 and shows the materials before the metal clip is forced around the ends of the pigtails.

Fig. 5 is a view similar to Fig. 4 showing the condition of the materials after the Y which receives a mixture ofl finely divided ingredients including metal powders and a suitable filler such as powdered graphite. The metal powders may include copper, tin and lead. A predetermined quantity o f powders is introduced into the molding space and a briquetting unch 16 compresses the powders into a predetermined form 17 shown in section in Fig. 2. This operation used for starting motors of automobile types of internal combustion engines maybe sinltered in about one minute time.

Heretofore, it has been the practice to attach the pigtails of a brush to a metallic body or clip by soldering. I have discovered that I may join the free ends of the pigtails of the brush with a clip by means of a sintering operation which may take place, if

desired, simultaneously with the sintering of the brush body and the bonding of the pigtails thereto. This operation is carried out in the following manner: After forming the article including the compressed powder form 17 and the pigtails 13, the free ends of the pigtails are cleaned preferablyl by dipping into a weak aqueous cyanide solution. While the ends of the pigtails are still moist they are dipped into copper powder such as is used in the mixture of powdered metals for forming the brush body. The small cylindrical portions 18 indicated in Figs. 3 and 4 will be some of the copper powder clinging to the ends of the pigtails 13. The mol yed ends of pigtails 13 are then laid upon a metallic clip 19 which has been previously cleaned by dipping preferably in a weak aqueous cyanide solution. The ends 20 of the clip 19 are then compressed around the coated ends of the pigtails as indicated at20 in Figs. 5 and 6. Some of the powder of the portion 18 is compressed between each pigtail and the end 20a of the clip while the clip is formed around it. Other portions of this powder are pressed into holes '21 and 22 which have been previously formed in the clip. These portions of vpowder are designated by numerals 21a and 22 in Figs. 5 and 6. Instead of applying the copper pigtail between the ends of the pigtails in the manner described, the powder could be-mixed with a temporary binder to provide a paste which could be molded around the ends of the pigtails.

- The assembly of the molded body 17, the pigtails 13, and the clip 19. is immersed in a sintering bath composed of molten salts of alkaline metals. The temperature of the bath and the time of immersion are sufficient to provide for the sintering of the metallic particles of the molded body 17 into a coherent metallic structure. The time required for sintering the metallic particles into a coherent mass is sufficient for joining the pigtails to the clip. After sintering the work is quenched in water and is then immediately ready for finishing the commutator engaging surface of thc brush. Examination of the joint between the pigtail and the clip shows .that the strands of the pigtails merge into the united copper powder which has been sintered and that this coating mergesinto the metal of the clip so that the clip and the pigtail are in effect an integral body. The quantities of powder which were forced into the holes 21 and 22 are united with the clip 19 as well as to the pigtails. These bodies 21a and 22a provide anchors for making secure the connection between the pigtail and the clip. v The use of the present invention to join the leads of a brush to a metal clip is only one of the many ways in which the present invention can be applied, as it isapparent that the joining of the flexible conductors to the meta-l clip may be accomplished without a brush structure being present; Generally the present invention provides a bond between metallic electrical conductors which l is not subject to corrosion due to traces of flux acids which may be present if the joint is made by soldering. A further advantage is that the bond has substantially as great a conductivity as the metal of the parts united. In the application of the present invention to the manufacture of dynamo brushes the invention possesses the additional advantage of the reduction of time in the manufacture, since the clip is joined to the pgtail during the same operation in which the metallic particles are sintered to form a united metallic structure and in which the pigtails are united with the brush body.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.-

What is claimed is as follows: n v 1. The method of uniting metallic bodies which consists in placing a metal powder between them; and, while the bodies are maintained in juxtaposition with the metal powder between them heating the powder in a. non-oxidizing atmos here at a tem erature and for the tlme su cient Ato cause .t e metal particles to unite' with each other and with the metal bodies. l

2. The method of uniting metal bodies which consists in placing between them metal powder including a metal of the bodies to be united; and, while the bodies are maintained in juxtaposition with the metal powder between them heating the powder in a non-oxidizing atmosphere at a temperature and `for a time sufficient to cause the metal particles to unite with each other and with the metal bodies.

3. The method of uniting two bodies of the same metal which consists in placing between them a powder of the same metal as the bodies; and, while the bodies are maintained in juxtaposition with the metal powder between them heating the powder in a` non-oxidizing atmosphere at a temperature and for a time sufiicient to cause the metal particles to unite with each other and with the metal bodies.

4. The method of uniting two copper bodies which consists in placing between them powdered copper; and, while the bodies are maintained in juxtaposition with the metal powder between them heating the powder in a non-oxidizing atmosphere at a. temperature and for a time sufficient to cause the metal particles to unite with each other and with the metal bodies.

5. The method of uniting metallic bodies which consists in lacing a metal powder between them; and, while the -bodies are maintained in juxtaposition with the metal powder between them, heating the whole to a temperature and for a time suiiicient to cause'the metal particles to unite with each other and withp'the metal bodiesyby immersing said whole in a heated bath of molten salts.

6. The method of uniting metallic bodies containing copper which consists in plwcin a powdered copper between them; an while the bodies are maintained in juxtaposition with the powdered copper between them, heating the whole to a temperature and for a time suliicient to cause the metal particles to unite with each other and with the metal bodies, by immersing said whole in a heated bath of cyanide salts of an alkaline metal.-

7. The method of uniting metallic bodies containing copper which consists in lacing a powdered-copper between them; an while the bodies are maintained in juxta sition with the powdered copper between, eating the whole to a temperature and for a time sufcient to cause the metal particles to unite with each other and with the metal bodies by immersing said whole in a heated bath with the powder between them, and in sinter-l ing the powder under non-oxidizing conditions to e'ect the union of the copper particles with each other and with' said parts.-

9. The method of uniting two metallic bodies which consists in providing one of the bodies with recesses at that part of the same which is to be attached to the other body, in placing metal powder between the bodies to be united 'in said recesses, and, while the bodies are maintained in juxtaposition with the powder between them and in said recesses, in sintering the whole under non-oxidizing conditions to unite the metal particles with each other and with the metal bodies.

10. The method according to claim 5 in which the bodies to be united are first cleaned4 with an aqueous solution of a salt used in the sintering bath.

11. Anvelectrical conductor comprising a flexible conductor, a metal clip, and a metal bond uniting the vconductor and cli said bond comprising united particles o? powdered metal.

12. The method of uniting metallic bodies which consists in placing metal powder only between them, and while the bodies are -maintained in juxtaposition with the metal powder between them, heating the powder in a non-oxidizing atmosphere at a temperature and for a time sufficient to cause the metal particles to unite with each other and with the metal bodies.

13. The method of uniting metal bodies .which consists in placing between them metal powder including a metal of the bodies to be united and while the bodies are maintained in juxtapositionv with the metallpowder between them, heating the powder in a non-oxidizing atmosphere at a temperature less than the melting point of said bodies and for a time sufficient to cause the metal particles to unite with each other and with the metal bodies.

\ 14. The method of uniting two copper bodies which )consists in placing between them powdered copper; and while the bodies are maintained in juxtaposition with the metal powder between them, heating the powder in a non-oxidizing atmosphere at a temperature less `than the melting point of copper and for a time sulicient to cause the metal particles to unite with each other and with the metal bodies.

In testimony whereof I hereto aix my signature.

'CHARLES FREDERIC SHERWOOD. 

